Percussion tools like the above can be used mainly for breaking up concrete and other demolition jobs, but also for example to remove rivets, whence the common English term “rivet buster” or rivet hammer. The percussion tool has an interchangeable insert tool and can be adapted to a number of different application fields by replacing the tool. The percussion tool comprises a buffer to absorb the impact energy that is not transmitted to the work site. The buffer wears down successively during use of the percussion tool and has to be replaced when it reaches a certain degree of wear. There is a risk that the operator will forget to replace the buffer and thereby risks causing internal damage to the percussion tool.
When working with percussion tools of this type, the operator presses the tip of the insert tool against the work site or the object being worked on. In this way, most of the impact energy generated in the percussion tool is transmitted to the work site. Under this type of normal use of the percussion tool, only slight wear will occur on the buffer. By far the greatest wear on the buffer occurs in cases when the operator leaves the percussion tool running, i.e., leaves the pressurised air to continue acting on the percussion tool, without the insert tool being in contact with the work site (in English, “backhammering”). This is a type of faulty use by the operator, who is instructed to avoid this.
The effect of the above-described pattern of use means that the buffer of the percussion tool is successively worn down and has to be replaced. The wear can have a rapid course, since the percussion tool will strike continually for as long as pressurised air is working on it. The striking frequency often lies in the range of 10 to 50 Hz. If the operator forgets to replace the buffer, this will result in costly damage to internal parts of the percussion tool and halting of operations.
With known percussion tools of this type it is difficult for the operator to know when it is time to replace the buffer. It is also quite possible for the operator to make the mistake of using the percussion tool in the above-described manner, even though the buffer is fully worn down or has reached an unacceptable degree of wear.
The percussion tool in British patent 2084916 is designed so that it can only be operated when the operator is pressing the tool against the work site. However, the solution is not applicable to pneumatic percussion tools of the above type with buffer, since the English percussion tool is electrically operated and lacks a buffer.